The present invention relates to voltage regulators and in particular to switching voltage regulators for DC-to-DC voltage regulation.
Today""s microprocessors operate at high current and low voltage, rendering conventional power delivery techniques, e.g., those that use simple buck regulators, impractical. For example, to deliver power to a microprocessor at 1.2V and 120 A, a system with a 12V power supply requires such voltage regulators to include a relatively large and cumbersome inductor and relatively expensive input capacitors to handle the current. As a result, in many applications multi-phase DC-to-DC converters are being used to meet modern microprocessors"" power delivery requirements. Although such a device works like a buck converter, it includes several sets of inductors and pass and flywheel components that are switched on and off in separate phases.
Such a voltage regulator can use smaller inductors and fewer expensive input capacitors, because the switching load is distributed over several phases. This enables easier mounting of components and reduces switching transients. Each phase of such a multi-phase DC-to-DC converter is pulse width modulated to regulate the voltage. Unfortunately, there is a cost associated with that capability. A special controller is required to change the duty cycle for each phase. In addition, varying the duty cycle from one phase to the next can cause significant current imbalances.
Accordingly, there is a need for an improved multi-phase voltage regulator. There is a need for such a device that does not require a special controller to change the duty cycle for each phase, and that is not susceptible to meaningful current imbalances. The voltage regulator of the present invention provides such a device.